Question

Zach weighs 180 pounds and is running on a treadmill at a constant speed and slop. You are measuring Zach’s volume of oxygen consumed (VO2) and volume of carbon dioxide produced (VCO2) while he is running. You find that his VO2 is 32 ml ∙ kg-1 ∙ min-1 and his RER is 0.9. Based on this information how many kcal is Zach expending per minute? Assuming Zach exercised at this intensity for 10 minutes, how many total kcal did he expend?

Answer 1

Respiartory exchange ratio( RER) = VCO2 / VO2

Given

RER= 0.9

VO2 per kg = 32ml/kg min.

Given the mass of Zach= 180 pounds= 81.64 kg

Therefore VO2 of Zach= 32 x 81.64 ml/min = 2612.8 ml/min

VO2 in L/min = 2612.8/1000 L/min

=2.61 L/min

Kcal spent per minute = (VO2 in litre/ min X RER calorific equivalent)

RER calorific equivalent is a constant for RER =0.9 and equal to 4.924

= 2.61 x 4.924 = 12.85 Kcal/min (First answer)

If he continues the exercise for 10 mins, we just multiply it by the number of minutes

= 12.85 Kcal/min x 10 min

= 128.5 Kcal (second answer)